On Wed, 19 Oct 2005 04:52:58 -0500, granpaw
wrote:

Bullet resistant too... great for sunglasses sold on eBay.

http://www.af.mil/news/story.asp?id=123012131

(snip)

I wonder if the 'legend' of transparent aluminum is an outgrowth of
the use of an aluminum film for use in astronomical mrrors. The film
develops a hard oxide coating that is transparent and durable.

It isn't as reflective as silver but has a much longer lifetime
because it doesn't tarnish. It was a very important development in
telescope technology.

Soames